Ingot mold



is subjected to enormous strains,

v stool is relatively cool 1 more especially to ingot molds,

Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE l WILLIAM: HAIG MIAGE, 0F GIRARD, OHIO, ASSIG-NOR TO 'VALLEY MOULD AN D IRON CORPORATION, 0F HUBBABD,OHIO, A CORPORATION 0F NEW YORK INGo'r nom) Application led September 1, 1926. Serial- No. 132,923,

This application relates tometallurgy and stools, and thelike.

L vThat portion of an iron ingot mold or stool which comes into contact with or is adjacent to the molten metal, such as molten steel, when the ingot mold is in use becomes very highly heated, and cools down as the molten steel, comprising the ingot, freezes. This portion of the ingot mold Wall orstool because the thick metal wall of the iron ingot mold or when the steel is first poured in and is quickly raised to a high temperature on the matrix side of the wall, while the Youter side of the wall is relatively cool until suflicient time has elapsed to permit the heat tol travel through the ingot mold wall. The repeated heating, and cooling of the ingot mold by repeated use in casting ingots, subjects the ingot mold to wear which sooneror later destroys the usefulness of the ingot mold. The cost of ingot mold replacement is necessarily an element which 'enters into the final cost of the steel produced. Ity there-- fore follows that the longer the life of the ingot mold can be prolonged before the ingot mold is Worn out, the more economical is the production of ingotsF from such an ingot mold.

One of the factors entering into the de` structionof the ingot mold by use is thev formation of what are termed in the art fire fi'acks. These cracks start at the matrix surface and gradually vdeepen and widen as the ingot mold is used. Fire-cracks usually start Where an edge of a flake of graphitic carbon extends to the matrixsurface of the ingot mold. These cracks may cause chunks or pieces of the matrix side Wall to spall off, thus producing aroughenedgsurface which ruins the ingot mold. Furthermore, the iirecracking action increases the erosive effect of a hot stream of steel where such stream strikes on the ingot mold or stool. The action `of erosion is also accelerated or in- .creased by a matrix wall of open grained cast iron, even before serious fire cracking bes to occur. Unfortunately, the vkind of metal which is best -suited for resisting the thermal strains set up by repeated heating and cooling of the ingot mold when in use has 'normally the qualities which are conduci've to re cracking. Therefore, an ingot mold having a matrix Wall of openY grained metal has a relatively short life.

The present invention overcomes the difcharacter as to combine withthe carbon in the molten iron when the ingot mold is being c ast to form carbides and to cause such gra phitic carbon as remains in this part of the ingot mold Wall lto tend to assume nodular or spheroidal forms instead of comprising graphitic carbon in iiake form such as is usually found in open grained metal. Y

The preferred manner or method of obtaining the desired results may be brought about by ap lying powdered or pulverized commercial erro-chrome preferably though not necessarily in a dry form to the matrix portions of the casting molds in which the ingot mold and stool are tov be cast.

The .matrix portion of the ingot mold is determined by the core of the casting set-up,

Iand the powdered or pulverized ferro-chrome may be applied to the core by any suitable vehicle which will cause this material to adhere to the substantially vertical faces of the core. One convenient vehicle for this purpose comprises blacking which is commonly used on cores for casting ingot-molds. Experiments have demonstrated that a satisfactory result is obtained by using ferrochrome powdered or pulverized to such finen'ess as to pass a forty mesh screen. Good results have also been obtained bythe use of both finer and coarser pulverized ferrochrome, and by mixtures of fine and coarse powders thereof.

'The results are improved by the addition ficulties heretofore encountered in ingot of subdances which give an exothermic reaction. Such a substance which produces this reaction satisfactorily for the present purposes is powdered aluminum mixed with any suitable oxide in proper proportions well known in the art. The aluminum is also beneficial for its physical effect in 'facilitating troweling or smoothing the ferro-chrome where it is a plied in dry powdered form, as is the pre erred way of applying it, to surfaces of the casting mold which are horizontal or of such inclination this method of application.

The following mixtures have produced very satisfactory results, and are given by way of examples of mixtures for carrying out the present invention.

Magnesium l 0.23 LJlarture D -hrome coa ting Percent ma qt c f t) by wigdt rome (69.9 r con en Magnesium (C. P.) 1.0 Chrome ore (40% Cr content) 6.0 Aluminum (C. P.) 10.0

(This mixture has molten resin as a ux.)

Hiature "E chrome-nickel coating-Dry 'powder Per cent by weight Ferro-chrome (69.9% Cr content) 14.63 Nickel (96.5% Nl content) 73.30 Anhydrous borax (Na-,BO 0.99 Chrome ore (%J CrgO, content) 6.99 Alum 2.69 Magnesium 1.40

Htten-e F chrome-manganese coating-Dry powder Per cent by weight Ibm-chrome (69.9% Cr content) c 61.42 Ferro-manganese manganese) 30.67 Anhydrous horax (NmBOf) 0.93 Chrome ore (55% Crg. content) 3.59 Aluminum 2.39 um 1.00

Mixture G chrome-titanium mating- Dry powder Ferro-chrome (69.9% Cr content) Nickel (96.5% Nl content Anhydrous bor-ax (Na=B40f^ Chrome ore (55.0% CrzO, content) Aluminum (C. P.)

as to permit- Magnesium (C. P.) 1.0 Linked oil (Sp. G. 0.93) 13.5

'Mixture I chrome-titanium coating (with anhydraus boraz) Per cent by weight Ferrcechrome (69.9% Cr content) 51.6 Ferrocarbonribminm 17.2 Anhydrous borax (NazBO, 0.7 Chrome ore (55.0% CrzO, content) 11.1 Aluminum (C. P.) 4.6 Magnesium (C. P.) 1.3 Linseed oil (Sp. G. 0.93) 13.5

invention may be of any shape or type and the grain closing material need be applied only to that part of the set-up which forms the matrix of the ingotmold or stool. The grain closing material appears to soak into or to be absorbed by the molten iron in such manner as to form a compound and where a chromium compound or metallic chromium is used, it appears to form chromium carbide and also a double carbide of chromium and iron, the highest percentage 4of which is adjacent the treated surface of t-he cast iron and lesser amounts are to be found at considerable depths in the cast iron. In other words, the process of the present invention forms anadmixture of iron and a chromium compound which soaks into the iron and closes the grain of the iron without leaving a coating of metallic chromium on the surface. There is no distinct line of demarcation between the chromium compound and the cast iron but on the contrary,l there is a thorough comingling of these materials which decreases in richness of the chromium compound from the surface until all trace of this compound disappears at a depth varying from the surface skin to one-half an inch, dependent on the amount of chromium compound used and the temperature vand condition of the molten iron.I The greater amount of the carbon adjacent the surface treated appears to be in the form Ofcombined double carbide of iron and chromium and such graphitic carbon as exists appears to be in the form of nodules or spheroids and there does not appear to be any pure chromium present in the finished article.

While chromium' compounds Vhave been referred to as the preferred substances, I have found that other ferro alloys will satisfactorily close the grain of thecast iron ingot molds; and as an example of other alloys contemplated by the present invention are ferro manganese; powdered or pulverized washed metal; powdered or ulverized white iron; and the ferro alloys o? tungsten, molybdenum. nickel, titanium and other metals of these characters.

The figure of the drawing illustrates in a conventional Way a vertical section through an ingot mold and stool according to the present invention in which the body 1 of the ingot mold and the body 2 of the stool are of ordinary cast iron. vThe matrix faces 4 of the ingot mold and the matrix faces 5 of the stool are impregnated with a grain closing substance such as ferro-chromeA or other ferro alloys above referred to produce fine close grained dense metal adjacent the matrix side lWall and which blends into the softer and more open grained metal adjacent the outer side of the Walls 6 of the mold and the outer side Aof the Wall 7 of the stool.

Having thus described my invention, what I claim is i l. An article of manu-facture comprising a cast iron -ingot mold having a dense close tough matrix side Wall comprising an alloy of iron adapted to resist fire cracking and WILLIAM HAIG RAMAGE. 

